Emergency Contraception – Consumer Health Info

What Is Emergency Contraception?

Emergency Contraception (EC) is a birth control method used after unprotected sex or when a primary form of contraception fails. It is generally used only in these specific situations and is not advised for use as regular contraception. It is also sometimes called “postcoital contraception.” EC is a contraceptive method that primarily works by either delaying ovulation or stopping implantation of a fertilized egg. It does not protect against sexually transmitted infections (STIs) and does not induce an abortion.

How Effective Is Emergency Contraception?

The chart compares the four types of EC and illustrates how effective they are as well as other things to consider when making a choice.

Emergency Contraception Type Prescription required? How long, after unprotected sex, is it effective? Overall effectiveness Things to consider
Levonorgestrel PillsNoWithin 1-3 days (most effective) but can be used up to 5 days after75-89%Most effective for people who weigh under 155 pounds. Effective for people between 155-195 pounds.
Ulipristal PillsYesWithin 5 days85%Not the best option for people whose current hormonal method of birth control (like the pill, patch, or ring) may have failed.
Oral Contraception PillsYesWithin 3 days~75%Effectiveness varies based on the birth control that is going to be used as EC.
Copper IUDYes; needs to be inserted by a doctor or nurse practitionerWithin 5 days99.9%Once inserted, can serve as the primary birth control method for 10-12 years (or until removed); effectiveness is not impacted by weight.

Additional Information on Emergency Contraception:

Emergency Contraception Pills

There are three types of EC pills available in the U.S. (they are also called “morning-after pills”). While each type of pill has its own pros and cons, it's important to never use two different kinds (like Plan B and ella) within 5 days of each other because the active ingredients may counteract one another and make the pills ineffective.

The first type is an EC pill that contains a hormone called levonorgestrel, which prevents an egg from being released from the ovary or being fertilized by sperm. This type of EC is sold under the brand names My Way, Plan B One-Step, Preventeza, and Take Action. This type of EC is most effective when taken up to 24 hours after unprotected sex, but it's still effective up to 72 hours after unprotected sex. Most levonorgestrel ECs are accessible over the counter (OTC) and do not require a prescription.

The second type is an EC pill that contains ulipristal, which prevents the egg's release, slows ovulation, and also thickens vaginal fluids so it's harder for sperm to reach the egg. This type of EC is sold under the brand names ella and ellaOne and requires a prescription. It is most effective when taken within 5 days of unprotected sex; unlike other EC pills, this type is just as effective for all 5 days (in other words, it doesn't become less effective over time). A person's weight has a big impact on this type of EC pill's effectiveness, and it is more effective than other EC pills for people who weigh 155 to 195 pounds. This type of EC does not work as well for people who weigh more than 195 pounds. The third type of EC pill is regular oral contraceptive pills that are taken in a larger number than usual. Oral contraception already includes hormones like levonorgestrel, so taking more than one pill at a time works as EC. The number of oral contraception pills to take in order for them to work as EC depends on the brand used. This chart lists the number of pills needed for an EC dose for many different brands of oral contraception.

This type of EC is less effective than the others and is more likely to cause nausea. Women should consult with a doctor, nurse, or family planning clinic before using this type of EC; oral contraception requires a prescription.

Copper IUD

The copper IUD can also act as EC. It prevents pregnancy by interfering with the way that sperm moves and makes it hard for sperm to get to the egg and also affects the uterus and Fallopian tubes. When used as EC, the copper IUD may act by preventing implantation, which is considered to be the beginning of a pregnancy. The copper IUD is sold under the brand name Paragard. To use a copper IUD as EC, a health care provider inserts it into a person's uterus within five days of unprotected sex. If you can't get an appointment to have the IUD inserted within five days after unprotected sex, use a different type of EC as soon as possible. This is the most effective type of EC and can then serve as your primary birth control for up to 12 years.

Which One is Right for You?
Planned Parenthood has an online quiz that can help you figure out which type of EC makes the most sense for you.



Other Resources:

  • The Mayo Clinic: a prestigious medical center with trustworthy medical information
  • Planned Parenthood: a non-profit organization that does research into and gives advice on contraception, family planning, and reproductive health
  • WebMD: a source of trustworthy medical news and information